Microprocessor based relays, also called digital relays, have a proven track record of reliability, with over 100,000 relayyears of field experience. For example, lets take microprocessorbased frequency relays picking up when frequency diverts by 0. Nov 08, 20 this is a recreation of the first paper i ever presented from the neta conference in 2001 that was the foundation of the relay testing handbook series. Advantages and disadvantages of microprocessor polytechnic hub. B microprocessor based relays microprocessor based relays incorporated analogtodigital converter adc to sample the analog signals incoming from instrument transformers, and used microprocessor to define the logic of the relay. Implementation and performance of synchrophasor function within microprocessor based relays 37 another issue is the required resolution of the internal oscillator. Abstractthis report covers issues concerning the security of electronic communication paths to protective relays. Revised edition released june 2009 previously presented at the distributech conference, february 2007 previous revised edition released february 2008.
Multiprocessor relays allow for 86 lockout relay functions to be moved into the relay logic, reducing the number of components in the system. Microprocessorbased distribution relays contribute to improved reliability and reduced costs on electric power systems. It is the goal of this paper to present the reader with some background material and discussions by which they can. Both the mib and pvd have the same high impedance operating principle, with the same limiting criteria of maximum short circuit current calculated from the number of feeders and the calculation of the minimum short circuit. The relays use programmable logic to reduce and simplify wiring. Then a relatively simple microprocessor does a slow speed ad conversion of the dc signal, integrates the results to create the timeover current curve response, and trips when the integration rises above a set point. Microprocessor is its speed, which is measured in hertz. Chapter 2 introduction to microprocessor based control. If x is greater than xl but less than x2 it sends the tripping signal after a predetermined delay. The question is whether such high sensitivity and accuracy are really required in relay protection of power units. Integral to microprocessor based relay tc2 cc in1 breaker status input in2 trip circuit monitor input optional. Though this relay has a microprocessor, it lacks the attributes of a digitalnumeric relay, and hence the term microprocessor. A fully integrated ied equipped substation with 25 breakers testing the full complement of data displayed on a local monitoring system and rtu. The microprocessor may use some kind of counting technique, or use the discrete fourier transform dft to implement the algorithm.
Experimental results with better relay characteristic performances and high flexibility for implementing the desired value of n, including noninteger values, are obtained. Microprocessor relays with logic and communication capabilities can accomplish this type of scheme by using either hardwired trip contacts or by using communication signals between each other to transfer statuses. Dec 28, 2015 fundamentals of microprocessor based relays 1. Reserve questions until the conclusion time limitation.
The statistical data introduced by the author coincide with data of other authors and con. Protecting distribution substation assets modern protection schemes with microprocessorbased relays abstract. The new relays deliver a host of benefits, including increased. Microsoft powerpoint relay scheme design using microprocessor relays.
Problems and solutions 335 periodicity once in 4 years only for electromechanical relays is established. Electromechanical relays had no significant drawbacks in their protection functions, but the additional features offered by the microprocessor technologies. Microprocessor is that these are general purpose electronic processing devices which can be programmed to execute a number of tasks microprocessor is its speed, which is measured in hertz. Tutorial on operating characteristics of microprocessorbased. B microprocessorbased relays microprocessorbased relays incorporated analogtodigital converter adc to sample the analog signals incoming from instrument transformers, and used microprocessor to define the logic of the relay. Reliability of microprocessorbased protective devices revisited 35 1940 1950 1960 protective relays design life expectancy 30 25 20 15 10 5 years to obsolescene 1970 1980 1990 fig. Description the powerlogic digital relay figure 1 is a multifunction, microprocessor based device which performs these functions. Numerical relays are based on the use of microprocessors. In this paper the implementation of an impedance relay using 8085 microprocessor is described.
That kit used for this purpose is vinytics vmc 8506 which has an inbuilt adc interface based on adc0809 chip and also some relays which can be turned on or off by providing simple 8085 instructions. Life cycle considerations for microprocessor relays. For instance, a microprocessor with 3 ghz, shortly ghz is capable of performing 3 billion tasks per second. Compared to static relays, digital relays introduce analogue to digital convertor ad conversion of all measured analogue quantities and use a microprocessor to implement the protection algorithm. By using the boolean simplification, we can represent the logic in a microprocessor based relay in a few different ways. Numerical relays protection and control products for power. Tests of microprocessorbased relay protection devices. Pullman, washington introducrlon advanced microprocessorbased distribution relays have features that improve distribution protection and aid in event analysis and testing references i, 2, 3, and 4. For the most effective protection, many utilities and industrial facilities are replacing aging electromechanical relays with new generation microprocessor based relays. Intelligent electronic devices ieds, have evolved over time in hardware and firmware with new features.
The results from the evaluation of the relays, combined 11 with the fieldobserved reliability life curve confirm that when relays are manufactured from highquality materials and highquality processes and the effects of aging ar e considered during product design, that microprocessorbased relays can reliably. Journal of microcomputer applications 1983 6, 1523 microprocessorbased distance relays badri ram and b. Life cycle experiences with microprocessor based relays and. Microprocessor based distance relays 19 reactance for the first zone of protection. The space requirement for the microprocessor based relay scheme is much less than the electromechanical relay scheme 5, 6. Now, microprocessor based digital relays are becoming the norm for new installations and many replacements, because of their improved protective capabilities, reliability, and additional features. This is a recreation of the first paper i ever presented from the neta conference in 2001 that was the foundation of the relay testing handbook series.
These relays feature advanced programmable functions which maximize flexibility and monitoring. Microprocessor relays provide many functions that were not available in electromechanical or solidstate designs. This 8085 kit based interface circuit controls 64 relays. Typical electromechanical relay scheme panel layout. Microprocessorbased distribution relays provide technical improvements and cost savings in several ways. Electromechanical and static relays have fixed wiring and the setting is manual. The relay can be on or off, that is, it has two stable states. The results from the evaluation of the relays, combined 11 with the fieldobserved reliability life curve confirm that when relays are manufactured from highquality materials and highquality processes and the effects of aging ar e considered during product design, that microprocessor based relays can reliably. Microprocessor based overload relay 3rb12 power supply. Now, microprocessorbased digital relays are becoming the norm for new installations and many replacements, because of their improved protective capabilities, reliability, and additional features. Chris is an electrical engineering technologist, a journeyman power system electrician, and a professional engineer. In a particular memory circuit, the addresses might start at 1oo0 and run consecutively.
Micro51 microprocessorbased overcurrent relays are used for phase and ground overcurrent protection in utility, industrial and commercial electrical power systems. The relay is operated in three zones with the required delay based on impedance. There are some advantages of microprocessor are given below. Microprocessorbased relays, also called digital relays, have a proven track record of reliability, with over 100,000 relayyears of field experience. Assuming 60 synchrophasors are produced per second, the synchrophasor interrupts are to be generated every 1,666. Operation and maintenance of protective relays and. Medium voltage products pr512 microprocessorbased self. Numerical relays are microprocessor based relays whereas the other relays are controlled electromechanically. Dec 24, 2012 compared to static relays, digital relays introduce analogue to digital convertor ad conversion of all measured analogue quantities and use a microprocessor to implement the protection algorithm. When microprocessor relays began to be applied in the mid 1980s, little to no consideration was given to endoflife.
The microcomputer sends a tripping signal instantaneously if the measured value of x is less than xi. Based control 29 is given a unique numeric address, which reprcsents its location just as a sreet adalrcss represents the location of a house, dala are written into memory and read out of memory, based solely on thoir address. Moreover they do not interfere with any electronic apparatus near the installation. Advances in microprocessorbased distribution relays. Relay scheme design using microprocessor relays a report to the. Microprocessorbased protective relays deliver more.
Data verified includes, but is not limited to that of scenario a, but also, alarms, control, status, events, reports. Microprocessor is that these are general purpose electronic processing devices which can be programmed to execute a number of tasks. A proposed scheme of overcurrent relays dealing with programming of the singleboard microcomputer tk85, built by nec around intels 8bit 8085 microprocessor, is described. These refays use algorithms similar in principle to their electromechanica1 counterparts. The references provide the required background knowledge and allow for further reading to explore some of the topics in greater detail. Implementation and performance of synchrophasor function.
Electromechanical relays had no significant drawbacks in their protection functions, but the additional features offered by the microprocessor technologies encouraged the evolution of. Numerical relays protection and control products for. Microprocessorbased distribution relay applications schweitzer. Microprocessor based protective relays deliver more information and superior reliability with lower maintenance costs richard d. He is also the author of the relay testing handbook series and founder of valence electrical training services.
Ppt microprocessor based power system protection powerpoint. Commissioning microprocessor based ied communication. Chakravarty bihar college of engineering, patna 800 005, bihar, india this paper presents a microprocessorbased distancerelaying scheme suitable for the protection of ehv lines. Implementation, conflicts, and corrective actions steven v.
Similarly, the output of a logic function is activated, that is, high or deactivated, that is, low. Such relays are also termed as microprocessor type protective relays. The relays provide protection for bus faults, breaker failure, and highside transformer blown fuse detection at no or minimal additional cost. A big difference between conventional electromechanical and static relays is how the relays are wired. In utility and industrial electric power transmission and distribution systems, a digital protective relay is a computer based system with software based protection algorithms for the detection of electrical faults. The goal of this paper is to contribute to the better understanding of microprocessor based 87l relays and bring. Dear sirs, we would like to thank you for your patronage and interest in our sphere of activityand products.
Fundamentals of microprocessor based protective relays suhag patel, p. Microprocessorbased protective relays applications in. Microprocessorbased distribution relay applications. Today we now find ourselves in the 30 year mark for the first generation microprocessor relays. Commissioning microprocessor based ied communication systems an65a00 6 b. For the most effective protection, many utilities and industrial facilities are replacing aging electromechanical relays with new generation microprocessorbased. Electric utilities company of nigeria eucn have traditionally used electromechanical emr distance relays for the protection of transmission lines in the past.
Relay logic is very important to understand the microprocessor based relay. The functions of electromechanical protection systems are now being replaced by microprocessorbased digital protective relays, sometimes. The article is a continuation of a set of the authors previous publications about the reliability of the microprocessorbased protective devices. Adv ances in microprocessorbased distribution rela vs edmund 0. Understanding microprocessor relay logic basic digital. Microprocessor based distribution relays contribute to improved reliability and reduced costs on electric power systems. In the event of a fault, protective relays protect electrical systems, equipment, and people from serious damage and injury. Distribution substations at electric cooperatives and municipal utilities have historically involved simple protection schemes consisting of feeder circuit overcurrent, reclosing, and transformer protection, either with highside.
Microprocessor based overload relay 3rb12 free download as powerpoint presentation. Micro51 microprocessor based overcurrent relays are used for phase and ground overcurrent protection in utility, industrial and commercial electrical power systems. From the viewpoint of reliability, a statistical study between 2000 and 2009, posted by a. The micro51 operates from conventional 5a or 1a secondary current transformers. Relay logic is very important to understand the microprocessorbased relay. Study and analysis of modern numerical relay compared to.
Numerical relays are microprocessorbased relays whereas the other relays. Microprocessorbased relays provide technical improvements and cost savings in several ways. In short, a phase comparator compares two input quantities in phase angle vertically irrespective of the magnitude and operates if the phase angle between them is pdf file. Microprocessorbased overcurrent relays article pdf available in ieee transactions on industrial electronics ie331. Understanding microprocessor based relay logic part 1.
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